Direct drive variable ratio hydraulic transmission of the automatic or manual type



Feb. 24, 1959 A. SCHOTT 2,874,533

DIRECT DRIVE VARIABLE RATIO HYDRAULIC TRANSMISSION OF THE AUTOMATIC ORMANUAL TYPE Filed Nov. 18, 1954 6 Sheets-Sheet 1 INVENTOR.

LAWRENCE Fl. SCHOTT ATTOR NEXS L. A. SCHOTT 2,874,533 IABLE RATIOHYDRAULIC TRANSMISSION AUTOMATIC OR MANUAL TYPE Feb. 24, 1959 DIRECTDRIVE VAR OF THE Filed Nov. 18, 1954 6 Sheets-Sheet 2 INVENTOR. LAWRENCEH. SCHDTT mmm Feb. 24, 1959 L. A. SCHOTT 2,874,533

DIRECT DRIVE VARIABLE. RATIO HYDRAULIC TRANSMISSION OF THE AUTOMATIC ORMANUAL TYPE Filed Nov. 18, 1954 e Sheets-Sheet 3 mm m E. A Q R M N E w Qm Wm kw IVQ & 1: l N W/kf/ mm 8 Axfi Y a x wm KS y 1 km w Feb. 24, 1959A. SCHOTT DIRECT DRIVE VARIABLE RATIO HYDRAULIC'TRANSMISSION OF THEAUTOMATIC 0R MANUAL TYPE Filed Nov. 18, 1954 6 Sheets-Sheet 4 Feb. 24,1959 Y Y sc o -r 2,874,533

DIRECT DRIVE VARIABLE RATIO HYDRAULIC TRANSMISSION OF THE AUTOMATIC ORMANUAL TYPE Filed Nov. 18, 1954 6 Sheets-Sheet s jam WW rarwz/S! Feb.24, 1959 SCHOTT 2,874,533

DIRECT DRIVE VARIABLE RATIO HYDRAULIC TRANSMISSION OF THE AUTOMATIC ORMANUAL TYPE Filed Nov. 18, 1954 6 Sheets-Sheet 6 IN V EN TOR.Azzx/rerzce fl-ScZy? BY $144, 44, aal/ul-b DIRECT DRIVE VARIABLE BATH)HYDRAULIC TRANSMISSION OF THE AUTOMATIC OR MANUAL TYPE Lawrence A.Schott, Detroit, Mich. Application Novemher 18, 1954, Serial No. 459,782

6 Claims. (CI. 60-19) This invention relates to transmissions, andparticularly to a transmission of the fluid type, and is acontinuation-in-part of application Serial No. 187,434, filed September29, 1950, now U. S. Patent No. 2,706,384.

The invention relates in particular to a hydraulic transmission whichprovides a variation of torque between the driving and driven shaftswhich varies from a maximum ratio to a direct drive without any feel ofchange of shift in the mechanism. The transmission is of suchconstruction that as the torque requirement changes the speed and torqueoutput changes and the resulting change occurs gradually and uniformly.As the torque requirement decreases and the speed increases, thedifference in speed between the two shafts gradually decreases to Zeroand the shafts will move into coupled driving relation without any fluidflowing. The hydraulic part of the transmission is employed only toprovide an increase of torque when additional torque is required,thereby eliminating a flow of fluid when the shafts are directlycoupled, the fluid being employed only to that degree that a change ofratio of speed and torque has occurred between the drive and drivenshafts.

This change will occur automatically if provisions are made forcontrolling the capacity of the variable volume fluid motor, or suchchange can be effected manually as torque requirements change. While theinvention structurally may assume various forms, by way of example theinvention embodies the use of a shaft driven from a source of powerwhich operates the propulsion means of a pump. The reactance portion ofthe pump is secured to a driven shaft to which the propulsion means of avariable fluid motor is secured. In this relation of elements the bodyof the fluid motor is secured in fixed position, and fluid from the pumpis delivered to the motor through a suitable porting member.

When no pumping can occur, the shafts are directly coupled, and whenincreased torque is required at the driven shaft this is obtained byincreasing the motor capacity from zero to the degree required. Thisprovision of increased motor capacity permits a change in speed betweenthe shafts which produces a degree of pumping action which is relativeto the change in speed between the shafts. The fluid from the pump isdelivered to the motor to apply power to the porpulsion means thereof toassist in driving the shaft, thereby increasing the torque on the shaft.

The percentage of lag permitted to the driven shaft relative to thedrive shaft is equal to the percentage of the capacity of the pump perturn which is provided. Thus, if 50% capacity is permitted to bedelivered each rotation of the driving shaft, the driven shaft will bepermitted to lag'one-half turn or 50%, thus providing a 2 to 1 ratiobetween the shaft speeds. The fluid from the pump is directed to themotor which assists the pump in turning the driven shaft this one-halfturn. It is to be understood that a fixed capacity pump may be utilizedwith a fixed capacity motor or a plurality thereof to provide atransmission having a fixed ratio and a direct 2,874,533 Patented Feb.24, 1959 2 couple drive if one motor is employed and a plurality ofdifferent fixed ratios and a direct couple drive if a plurality ofmotors are employed.

When the torque requirement decreases after the shafts have beenoperating at diflerent speeds, the capacity of the motor may bedecreased, and as the same amount of fluid from the pump cannot besupplied to the motor, the driven shaft speedwill be increased and thedegree of pumping will be decreased. When the variable capacity' motorhas been shifted to inoperative position, the pump can no longer pumpand the drive and driven shafts will be operating in direct, coupledrelation. When the variable fluid pump is provided with torque controlmeans for varying the requirement for fluid, in proportion to the,torque requirement, the change in relative speed of the drive and drivenshafts will thereby occur automati-- cally. When additional torque isrequired on the driven shaft slowing up the shafts, the capacity of themotor changes. automatically and the pump wil operate to a degreeproportionate to the difference of speed of the shafts. As the torquerequirement is reduced, the speed of the shafts increases, the capacityof the fluid motor is decreased, and the relative pumping action alsodecreases so that the speed of the driven shaft will continue to build.up until it is again directly coupled with the drive shaft. 7

Thus, it will be noted that the invention accomplishes a change of ratiobetween the driving and driven shafts through the control of hydraulicfluid. As the torque requirement increases, the ratio of rotationbetween the shafts increases, and as the torque requirement diminwhich,functioning as a motor, causes the driven shaft to operate at increasedspeed but at reduced torque. This occurs. when the capacity of the motorafter having reached zero. capacity has been moved to a reverse orpumping position which, up to a certain capacity, will drive the drivenshaft faster than the driving shaft, thus acting as an overdrive. Thisoverdrive effect can be built up until the capacity of the motor, actingin reverse, equals the capacity of the pump. When the capacity of themotor acting in reverse exceeds the capacity of the pump, a reversal ofrotation of the driven shaft occurs relative to the direction ofrotation of the driving shaft. The ratio between the speed of theshafts, the overdrive and the reverse operation thereof can beillustrated as follows. If the capacity of the motor is adjusted to havefive times the capacity of the pump, the pump will turn five times tosupply fluid to produce one turn of the motor and one turn to keep'upwith the motor. Thus the ratio between the driving and driven shaftswill be six to one. If the motor capacity is decreased to four times thecapacity of the pump, the pump will turn four times to supply fluid toproduce one turn of the motor and one turn to keep up with the motor.Thus the ratio will change to fiveto one. This relative relationshipwill continue until the capacity of the motor is zero, and as the pumpneed not turn to supply fluid it need only turn the one turn-to keep upwith themotor and, the ratio is one to one, at which time the shafts arein direct coupled relation.

The operation of the motor in a reverse direction subtracts from theturn required of the pump to keep up with 3 the motor and to this degreeof difference will the driven shaft increase its speed over the inputshaft. This overdrive etfect can be continued to a point where thecapacity of the reversed motor equals that of the pump which can beindicated at the point of infinity. Going beyond the indicated infinitypoint, .the motor will be operated by the fluid from the pump in areverse direction with a speed depending upon the set capacity of themotor in reverse. For example, if the motor is set to full capacity inreverse at say five times the capacity of the pump, the pump mustrelatively rotate five times to supply the required fluid to the motorto produce one turn of the motor. Actually the pump is required torotate only four turns, as a turn is picked up by the counter operationof the shafts, thus producing a four to one reduction in ratio.

Initially upon starting the driving member at low speed, the system isso set that the fluid produced by the operation of the pump is by-passedto tank and no resistance is offered to pump operation. When the by-passis shut olf, the fluid builds up a pressure to a permissible amount, thereactance to which drives the shaft so that relative relationship existsbetween the pump revolution and shaft revolution relative to therotation of the input shaft.

In a wobble plate type of motor, it is merely necessary to tilt thewobble plate in the opposite direction to that for direct drive toreverse the operation of the driven shaft. The volume of the motor mustbe larger, therefore, than the volume of the pump per revolution tocause the reversal of the propulsion means of the pump so that it willactually carry the reacting portion of the pump, and therefore thedriven shaft, in a direction counter to the rotation of the input shaft.

The wobble plate on the fluid motor may be pivoted offcenter relative tothe driven shaft toward the side which produces thrust from the outputpistons, which tends to force the wobble plate in a more angularposition as the pressure increases on the piston. Thus, the ratio ofsupply and demand of fluid between the pump and motor tends to increaseas the input torque increases, which is accomplished by increasedthrottle. The centrifugal force resulting from speed produced by theflywheel on the output shaft tends to straighten the wobble plate and inthis manner tends to retain the driving and driven shafts in directcoupled relation. This condition may be balanced to any desired degreeand will produce the effect of greater torque and increase of speeddirectly if more throttle is applied. When the throttle is increased,the increased power on the pistons of the fluid motor will cause itswobble plate to tilt due to the off-centered pivotal relation thereofand will counteract the flywheel which is tending to maintain the wobbleplate in no-stroke position. Thus, the increase in throttle produces anincrease in torque ratio which will be attempted to be overcome by theincrease of centrifugal force in the flywheel. In an automobile, theincrease in throttle produces an increase in torque which tends toproduce an increase in speed. As the speed of the driven shaftincreases, the centrifugal force of the flywheel overcomes the tiltingforce in the wobble plate, the wobble plate will be drawn tononoperating position and thereby have no capacity. As a result, thepump can no longer pump fluid to the fluid motor and a lock occurs inthe fluid system resulting from the fluid motor reaching no-volumecapacity, and at this point the shafts are driven at the same speeddirectly without any fluid movement.

Accordingly, the main objects of the invention are: to provide avariable ratio hydraulic transmission which is directly coupled in suchmanner that it can be driven at high speed for long periods of timewithout developing any excess heat; to provide a transmission with adrive and driven shaft interlocked by a closed fluid system be tween apump and motor when the shafts are driven at the same speed; to providea transmission having a drive and driven shaft with a fluid system whichis inoperative when the shafts are operating at the same speed and whichis operative to produce a flow of fluid from the driven shaft to thedrive shaft to increase the torque on the latter as the speed thereofdecreases; to provide a transmission having a drive and driven shaftwith a pump on the drive shaft and a variable capacity fluid motor onthe driven shaft, the differential in speeds between the two shaftsproviding a proportional degree of operation of the pump which providespressure to the fluid motor for increasing the torque on the drivenshaft; to provide a transmission having a drive and driven shaftinterconnected through a pump on the drive shaft and a variable capacitymotor on the driven shaft, the capacity of the latter of which iscontrolled centrifugally to meet the torque requirements of the drivenshaft when operating out of synchronism with the drive shaft; to providea transmission having a drive and driven shaft interconnected through apump and variable capacity motor, the operation of which increases withthe increase in differential speed of operation between the shafts toprovide increased torque to the driven shaft and which providesincreased speed of the driven shaft over the drive shaft when the motoris in overdrive position and which produces a reversal of operation ofthe driven shaft when the fluid motor is in reverse position; and, ingeneral, to provide a transmission which is simple in construction,positive in operation and economical of manufacture.

Other objects and features of novelty of the invention will bespecifically pointed out or will become apparent when referring, for abetter understanding of the invention, to the following descriptiontaken in conjunction with the accompanying drawings, wherein:

Figure 1 is a broken, plan view of an automotive vehicle having atransmission embodying features of the present invention;

Fig. 2 is an enlarged sectional view of the transmission illustrated inFig. 1, taken on the line 2-2 thereof;

Fig. 3 is an enlarged sectional view of the structure illustrated inFig. 2, taken on the line 33 thereof;

Fig. 4 is an enlarged sectional view of the structure illustrated inFig. 2, taken on the line 44 thereof;

Fig. 5 is an enlarged sectional view of the structure illustrated inFig. 2, taken on the line 55 thereof;

Fig. 6 is an enlarged sectional view of the structure illustrated inFig. 2, taken on the line 66 thereof;

Fig. 7 is a view of structure, similar to that illustrated in Fig. 2,showing a further form which the invention may assume;

Fig. 8 is a sectional view of the structure illustrated in Fig. 7, takenon the line 88 thereof;

Fig. 9 is a sectional view of a device, similar to that illustrated inFig. 1, showing a further form thereof;

Fig. 10 is a sectional view of the structure illustrated in Fig. 9,taken on the line 1010 thereof;

Fig. 11 is a broken sectional view of the structure illustrated in Fig.9, taken on the line 1111 thereof;

Fig. 12 is a sectional view of the structure illustrated in Fig. 9,taken on the line 12-12 thereof;

Fig. 13 is a sectional view of the structure illustrated in Fig. 9,taken on the line 13-13 thereof;

Fig. 14 is a sectional view of the structure illustrated in Fig. 9,taken on the line 14-14 thereof, and

Fig. 15 is a wiring diagram of the circuit for controlling the operationof the device illustrated in Fig. 9.

Referring to Figs. 1 to 6, the transmission of the present invention isillustrated in Fig. l as being applied to an automobile. It is to beunderstood that the application of the transmission to an automobile andthe specific structure employed in the transmissions is illustrated byway of example, as the transmission may be employed for many otherapplications and the form thereof may vary substantially from thatherein described. A chassis frame 10 is of the conventional type, havingan engine 11 supported thereon for operating through the transmission 12of the present invention.

The transmission 12, as illustrated in Figs. 2-6 inclusive, comprises acasing 13 having a removable cover 14 and bosses 15 and 16' at theopposite ends] A drive shaft 17 is journaled in a bearing 18 in the boss15, sealed against the passage of fluid from the inside of the casing 13by a sealing element 19. The shaft has a cuplike end 20 disposed withinthe casing, having four slots 21 in the cylindrical, inwardly extendingWall 22 thereof. A idriven shaft 23 is supported by bearings 24 in theboss 16 at the opposite end of the casing from the drive shaft 17 inalignment therewith. A hearing 25 is provided on the inner end of thedrive shaft 17 in which the forward end 26 of the driven shaft 23 issupported. Medially of the ends of the shafts, a valve plate 27 isdisposed in fixed relation with shaft 23.

The, forward end of the drive shaft 23-supports a barrel 28 of a pump 89mounted for rotation relative thereto. The barrel is provided with aplurality of cylinders 29 which are herein illustrated as being seven innumber, but it is to be understood that any number of cylinders may beprovided within the barrel. The barrel has four rollers 31 secured onthe outer periphery thereof and each located within a slot 21 of the cup20 on the drive shaft 17. A swash plate 32 is mounted on the forward endof the shaft 23, having an inner element 33 fixed to the shaft 23 bysuitable means herein illustrated as by setscrews 34. The outer element35 of the swash plate has four rollers 36 secured to the outerperipheral surface thereof, each located within a slot 21 of the cup 20.A piston 37 is mounted for reciprocation in each one of the cylinders 29of the barrel 23, having ballendedconnecting rods 38 connected to thepistons 37 and the outer element 35 of the swash plate 32 in theconventional manner. The inner and outer elements 33 and 35 areconnected in drive relation by balls or other suitable means to transferthe reactive thrust of the pump to the shaft 23. The location of therollers 31 and 36 within the slots 21 produces the synchronized rotationof the swash plate element and the barrel 28 relative to the shaft 23.

A barrel 41 of a motor 90 is mounted for rotation on the rearward end ofthe shaft 23 on the opposite side of the valve plate 27 from that of thebarrel 28. The barrel is secured by a pair of arms 42 to a boss 43 oneach side of the casing 13. The barrel 41 has a cylindrical portion 43extending therefrom, provided with four slots 44. The inner element 46ofthe swash plate is secured to the shaft 23 by a pivot 47 which may belocated on the center of the shaft but which is herein illustrated asbeing disposed in off-center relation therewith, for a purpose to behereinafter described. The outer element 48 of the swash plate 45 isprovided with four rollers 49 on the outer peripheral face thereof whichoperate in a slot 44 of the cylindrical extension 43 of the barrel 41.The interconnection of the rollers 49 in the slots 44 retains the outerelement 48 of the swash plate 45 from rotating so as to be maintained inalignment with the fixed barrel 41. The barrel 41 contains a pluralityof cylinders 51, herein illustrated as being seven in number, althoughany number of cylinders may be utilized which may be of the same orgreater capacity than the cylinders 29 of the barrel 28. Each of thecylinders contains a piston 52 which is interconnected by ballendedconnecting rods 53 to the element 48 of the swash plate 45 in theconventional manner. The inner and outer elements 46 and 48 areinterconnected by balls 59 or other suitable means to be in drivingrelation to each other. Thus, it will be seen that the-barrel 41 isretained in fixed relation to the casing and that the swash plateelement 43 is retained in fixed relation to the barrel.

A sleeve 54 is splined to the rearward end. of the shaft 23 for rotationtherewith while being shiftable longitudinally thereon. A flywheel 55 issupported by trunnions 56 on the sleeve 54. A link 57 is pivoted to theflywheel and to the inner element 46 of the swash plate 45. A spring58interconnects the flywheel to the sleeve 54 diametrically opposite tothe connection of the link 57 of the swashplate. A pair of flanges 59extends outwardly from the sleeve 54, providing a channel in which aroller 61 extends, the roller being mounted on an operating arm 62mounted on an operating shaft 63 which is journaled in apertures inbosses 64. The operating rod 63 extends through the casing and through apacking gland 65 in fluid tight relation therewith.

The valve plate 27 is provided with a fluid delivery passageway 66 onone half thereof and a fluid discharge passageway 67 and a fluid intakepassageway 68 on the opposite half thereof. The fluid'discharge slot 67has a discharge aperture'69 and the fluid intake slot has an intakeaperture 71, the apertures 69 and 71 communicating with the interior ofthe casing 13. The discharge slot 67 is connected by a by-passpassageway 72 to a valve seat 73 on the center line of the shaft 23.A'by-pass passageway 74 interconnects the fluid delivery passageway 66to the seat 73. A rod 75 extends through the forward endof the shafthaving a valve end 76 which is movable into engagement with the valveseat 73. The rod has its forward end secured by a pin 77 to a collar 78mounted exteriorly of the shaft 23. The pin 77 operates within a slot 79through the walls of the shaft. A pair of flyweight'ball governors 81 ismounted on the drive shaft 17 on the base of the cuplike element 20thereof, having fingers 82 disposed in engagement with the collar 78 formoving the collar and the rod 75 toward the rear end of the shaft 23,thereby seating the end of the valve 76 on the seat 73 and cutting offthe supply of oil from the delivery passageway 66 to the dischargepassageway 67. A spring about the rod 75 retains the valve end 76unseated and the governor 81 inoperative. Each cylinder 29 of the barrel23 and each cylinder 51 of the barrel 41 has a passageway 33 at the endthereof which is relatively movable into and out of engagement of thepassageways 66, 67 and 68, respectively. A fill plug 84 is provided inthe cover 14 of the casing so that the casing may be maintained full offluid after the cover is secured in sealed relation with the casing 13by the gasket 86 and the plurality of screws 87. The casing 13 is filledwith a desirable fluid through the fill plug 84', and the transmissionis then in condition for operation. For the purpose of illustration, thevalve 27 is shown offset from normal position. The outward movement ofthe pistons 37 should occur at the end of the slot 67, not at the centerthereof, as shown.

Assuming the transmission to be employed on an automobile, when theengine 11 is started, the spring 80 retains the flyballs in inoperativeposition at idling engine speed. When the speed of the engine 11increases, the flyballs overcome the tension of the spring 80 and startto seat the valve end 76. When the valve end is unseated during theidling of the engine, the shaft 17 is rotating and the shaft 23 remainsstationary. This permits the barrel 28 and wobble plate 32 to rotaterelative of the drive shaft 17. The pistons 37, when in pumpingposition, discharge the fluid from the passageway 83 into the passageway66 where it passes into the by-pass passageway 74 through the valve seat73 to the by-pass passageway 72 to the discharge passageway 67 and thedischarge aperture 69. In this manner, when the engine is idling, thepump is operating at the speed of the drive shaft, but is producing nodriving force to the automobile as the fluid is directly by-passed backinto the case.

When the speed of the engine increases and the valve seat 73 is beingclosed by the valve 76 due to the operation of the centrifugal device81, the reaction to the pump by the restriction to the flow of oilreacts on the driven shaft to produce its rotation. When the valve 76reaches closed position, the fluid can no longer be bypassed and isdirected from the passageway 83 of the pump to the passageway 66 of thevalve into the passageway 83 of the motor. This produces a drivingoperation of the motor to an amount depending upon the degree of torquerequirement on the shaft 23, and as the torque requirement decreases,the speed of rotation of the shaft 23 Will pick up until it reaches thesame speed as the drive shaft 17 and the shafts will operate in directcoupled relation. This occurs by reason of the fact that the pumping ofthe fluid into the motor provides a drive force to the shaft 23 by themotor, the reactance to which applies a force back through the pump,which also produces a driving relation on the shaft 23. As the speed ofthe shaft 23 increases, the centrifugal force of the flywheel 55 willreduce the capacity of the motor which will apply a further resistanceto the operation of the pump, the reaction to which will furtherincrease the speed of the shaft 23, and if the torque load permits theshaft 23 to continue to build up speed, the wobble plate 45 will bemoved to neutral position so that the motor can no longer function, thepump can no longer pump and the two shafts will be operated at the samespeed interlocked by the inability of the fluid to pass from the pump tothe motor.

Should the torque requirement of the driven shaft thereafter increase,the operation of both shafts will slow down, the flywheel will tilt andshift the wobble plate of the motor to provide capacity thereto, and thepump will start operation to provide fluid to the motor as the drivenshaft slows down. The fluid from the pump delivered to the motor addstorque to the shaft 23, and if the shaft should further slow down due tothe reduction in centrifugal force in the flywheel, the flywheel will beshifted by the spring 58 and the wobble plate 45 of the motor will befurther shifted to further increase the motor capacity, the speed of thepump will be increased to supply fluid to the motor, which will addadditional torque to the shaft 23 until a balanced condition is reached.

When the torque requirement on the shaft 23 is reduced, the speed ofboth shafts increases, increasing the centrifugal force of the flywheel55 which operates to decrease the capacity of the motor, thereby forcingthe fluid being pumped to react on the driven shaft to increase itsspeed, and as the speed of the driven shaft continues to increase as thetorque requirement decreases, it will again become directly coupled withthe drive shaft 17.

When a reverse operation of the shaft 23 is desired, the operating rod63 is actuated to move the arm 62 and shift the sleeve 54 toward therear end of the shaft 23, thereby reversing the slope of the wobbleplate 45 and thereby reversing the action of the motor 90 when thecapacity of the motor 90 is greater than that of the pump to cause theshaft 23 to operate in a reverse direction. I n between the neutralposition of the wobble plate 45 and its reverse position, an overdriveposition obtains in a manner as pointed out hereinabove. The actionabove described occurs when the wobble plate element 45 is pivoted tothe shaft 23 on the center line or when pivoted off-center thereof, asillustrated. When in off-center. relation, an advantage is provided inthat when the speed of the engine 11 is increased the increased supplyof fluid from the pump 39 produces increased thrust on the piston of themotor 90 and the differential between the length of arm of the wobbleplate element 46 and each side of the center of the shaft 23 tends toshift the wobble plate into a greater angular position and thereby applyan additional torque to the shaft 23. The flywheel tends tocounterbalance the tilting effect produced on the wobble plate due tothe increased speed of the shaft 23, thereby tending to bring the wobbleplate to neutral position and the shafts in direct coupled relation.Thus, a greater torque can be applied to the shaft 23 through increasingthe speed of the engine; that is to say, the same speed of driving ofthe automobile will be obtained by increasing the speed of the enginewhich will produce an increased speed of the drive shaft 17 over theshaft 23 and start operation of the pump 89 and the motor 90 until thetorque requirement is overcome, at which time the engine speed can bereduced to have the shafts again run at the same speed or the shaft 23will pick up additional speed to operate the automobile faster when theshafts are again running at the same speed due to the decrease of torquerequirement.

Referring to Fig. 7, a different arrangement of the parts of the motorand pump is illustrated to show'the possibility of employing differentconstructions, not only when utilizing the wobble type of pump andmotor, but it is to be understood that different types of pump and motormay be employed and advantages provided thereby. In the illustratedconstruction, the fluid pump 89 is substantially the same as thatillustrated in Figs. 2 to 6. A portion of a valve plate 91 is mounted tothe driven shaft 23, the other part 92 thereof being fixed to the casing13 (not shown in Fig. 7). A cylindrical bracket 93 extends rearwardlyfrom the plate 92 and is utilized for supporting a wobble plate 94thereon by a pair of trunnions 95 which are journaled in bearings 96 onthe element 93. The trunnions are secured to the outer element 97 of thewobble plate 94, the inner element 98 of which is secured to the shaft23 by a key 99, a universal joint or other connection which provides adrive connection therebetween while permitting the element 98 to rockrelative to the shaft 23. A barrel 101 is secured to the shaft 23 bysplines 102, so that the barrel and the element 98 of the swash platerotate in synchronism with each other and the shaft 23. The elements 97and 98 of the swash plate are interconnected by a plurality of ballbearings 103 or other mechanism strong enough to withstand the strain ofoperation. Suitable mechanism, herein illustrated as a lever 104, isemployed for tilting the swash plate 94 to thereby vary the capacity ofthe motor 105 which embodies the barrel 101 and swash plate 94.

The barrel 101 contains a plurality of cylinders 106 in whichreciprocating pistons 107 are mounted and connected by ball-endedconnecting rods 108 to the swash plate element 98. The passageways 83from the pump 89 communicate with an inlet passageway 109 on the intakeside of the pump and with the discharge passageway 111 on the pressureside of the pump. The bypassing of fluid from the passageways 111 to thepassageway 109 is cut off when the valve end 76 is seated on the valveseat 73. Thereafter, delivered fluid from the passageway 111 enters acylindrical passageway 112 in the valve plate 92 from which it isdelivered to a valve passageway 66 and the motor 105 from which it isdischarged into the valve passageway 67 and exhausted from the dischargepassageway 69 into the casing 13, not shown.

The structure illustrated in Figs. 7 and 8 operates in the same manneras the structure illustrated in Figs. 1-6, and is herein illustrated anddescribed for the purpose of showing the use of different capacities ofmotors and pumps and the different arrangement of the parts. It will benoted that the barrel 101 and the inner element 98 in the wobble plate94 rotate with the shaft 23, and that the valve plate part 92 is fixedto the casing 13. It has been pointed out hereinabove that the parts ofthe pump and motor may be of any form that is suitable and that theconnection may be made to the shafts in any desirable manner, just sothat the shafts can be directly coupled when no fluid is flowing andwhen fluid is flowing during the time the shafts are operating atdifferent speeds, the fluid is utilized for applying torque to thedriven shaft. The greater capacity of the motor over the capacity of thepump was found to be necessary to reverse the direction of operation ofthe driven shaft relative to the drive shaft when the direction ofoperation of the motor is reversed. It is to be understood that in theconstruction illustrated in Figs. 1-6, the capacity of the motor andpump may be changed, one relative to the other, to meet the specificrequirement of output speed and torque.

Referring to Figs. 9 to 15, a further form of transmis sion device isillustrated that which resulted from continuous development of theoriginally shown structure. A case 120 is secured in fixed position inthe vehicle or on a base of a machine on which the transmission isemployed. A shaft 121, which is connected to the power source, issupported on the forward end of the case in a bearing 122. The oppositeend of the shaft supports a drive gear 123 of a pump 119. Forwardly ofthe drive gear 123 a sleeve bearing 124 and rearwardly of the drive geara sleeve bearing 125 support the shaft within the motor casing 126 andthe pump casing 127, both of which rotate within the case 126 with orrelative to the shaft 121. The pump casing has a driven shaft 128extending therefrom rearwardly of the casing and sealed thereto by asuitable seal 129. The rear end of the pump casing is supported withinthe rear end of the case 120 by a bearing 131. Within the pump casing aplurality of driven gears 132 are mounted on stub shafts 133, and whileany number of gears may be provided, in the present arrangement asillustrated in Fig. 13, three gears are employed. Each gear 132 has anintake port 134 and an outlet port 135 communicating therewith. A plate136 contains three passageways 137 which communicate with the outletport 135 of the pump and three passageways 138 which communicate withthe inlet port 134 of the pump.

'Between the motor casing 126 and the pump casing 127 a slidable valveplate 139 is mounted. The valve plate has a central opening 141 intowhich the high pressure fluid from the outlet passageways 137 of thepump are discharged. Centrally about the sleeve 124 on the shaft 121 acircular plate 142 is mounted for rotation with the motor casing 126.The circular plate contains three notched passageways 143 which arealigned with the outlet passageways 137 of the pump. A motor port plate144 is secured to the cylinder body 145 of the motor 140 by a pluralityof screws 146. The plate has circular recesses 147 therein, one for eachof the cylinders 148 in the cylinder body and each recess communicateswith an elongated slot 149 in the opposite face of the plate whichcommunicates with the high pressure opening 141 in the center of theshiftable plate 139 or with the low pressure area 151 within the ringbody. This low pressure area is provided by annular slots 152 and 153 onopposite sides of the ring body which communicate with each otherthrough apertures 154. The slot 152 receives the oil discharged from theslots 149 in the plate 144 when communicating therewith, which oilpasses into the slot 153 through the apertures 154 and then into theintake port 138 of the pump 119. Within the face of the plate 136 of thepump, aligned with the slots 149 in the plate 144, a plurality of slotsv155 are provided of the same shape and area as the slots 149. The slots155 balance the pressure on the plate 139 and permit the passage offluid from the high to the low side of the pump when the plate 139 is inneutral position.

As indicated above, the cylinder body 14-5 has a plurality of cylinders148 provided therein, herein illustrated as nine in number. Each of thecylinders contains a piston 156 having a universal ball type connection157 with a piston rod 158, the opposite end of which contains a ball159. It will be noted that the cylinders are disposed at an angle to thedrive shaft 121 to obtain a greater length of stroke while concentratingthe pressures at the ends of the cylinder as close as possible to thecenter of the shaft 121 to reduce the application of pressure, and thetendency to deflect the plate 144 which would bind the shiftable plate139. A swash plate control mechanism 161 embodies an outer ring 162having a plurality of ball recesses 163 therein for receiving the balls159 on the ends of the piston rods 158. The ring 162 is supported byballs 164 on a trunnion ring 165 which has a pair of trunnions 166thereon supported on needle bearings to the fixed case 120. A universaldriving joint 167 is secured to the sleeve 168 on the forward end of thecylinder body 165 by screws 169. The uni versal joint is secured to thering 162 by a plurality of screws 171. The universal joint is of thestandard driving type such as that used for driving the propeller shaftof an automotive vehicle, the one herein illustrated being the Rzeppatype of joint.

For shifting the angularity of the swash plate 161, a control cylinder172 is provided mounted in the forward end of the case 120 having ahollow piston rod 173 supporting a piston 174 within the cylinder. Thehollow piston rod 173 functions as a cylinder when disposed in relationto a rod 175 extending therein from the center of the body of thecylinder. A spring 176 within the cylinder urges the piston 174 to therear end thereof. A driven gear 177 is mounted on the sleeve 168 fordriving a pump shaft 179. The shaft drives a pair of pump gears within apump 131 which is immersed in the oil within the bottom of the case. Apressure line 182 from the pump 181 is connected to-the rear end of thecylinder 172 in position to urge the piston 174 to the forward endthereof. This pressure is accurately controlled by the use of a conduit133 which extends to i the engine operation.

the top of the, case 128 and projects rearwardly therealong. The conduithas spray apertures 134 therein of a size to control the pressuredelivered from the conduit portion 182. The oil spray besidescontrolling the pressure cools and lubricates the driven parts of thepump 119 and motor 144 A conduit 185 at the forward end of the cylinder172 is connected to the intake manifold of the engine for varying thepressure Within the cylinder conforming to A conduit 186 on the outsideof the case 129 extends from the lubrication pump of the engine andpasses into the case 121) through the conduit 187 which is sealed to thecase 126 by a packing gland 188. A conduit 189 extends from the conduit182 through a check valve 191 to the conduit 187 which contains anaccurately gauged orifice 192 for controlling the amount of fluiddelivered to the conduit 187, tothereby permit pressure to be built upin the conduits 182v and 183. This check valve arrangement is desirablefor providing pressure when the engine is stalled and the car is to bepushed to start the engine. This. arrangement, provides pressure forshifting the plate 139 out of its neutral position so that a drive willbe had through the transmission to the engine.

The plate 139 has a piston 193 containing oil reservoirs 194 and 195which communicate with each other through a passageway 196. A pair ofballs 197 and 193 are interconnected by a rod 199 to form a unit valveassembly. These balls will be shifted to engage one or the other mouthsof the passageway 196 for sealing elf one of the reservoirs relative tothe other.

The conduit 187 is connected into the passageway 1 96 and a conduit 201extends from the passageway 196. and: is provided with an orifice forthe discharge of the fluid at an accurate predetermined rate, therebycontrolling the pressure of the oil within the passageway. A flexibleconduit 202 connects the reservoir to the interior of the hollow pistonrod 173 of the cylinder 172. A passageway 203 connects the low pressurearea of theplate 139 to the reservoir 194 and a passageway 2114 connectsthe 11 and high pressure to be delivered to the hollow piston rod 173.When the operators foot is removed from the accelerator, the pressureimmediately reverses so that the high pressure will be on the lower sideof the plate, thereby shifting the balls 197 and 198 to a reverseposition so that the fluid from the conduit 187 will pass into the pump119 and motor 140 through the conduit 204 and the pressure to the hollowpiston rod drops to the orifice pressure of the conduit 201, permittingthe rod to shift -the swash plate of the motor to no-stroke position sothat a one-to-one ratio is provided between the shafts 121 and 128.

The conduit 186 is connected into a four-way valve 205, having solenoids206 and 207 at opposite ends thereof for shifting a spool which controlsthe flow of fluid either fromthe conduit 208 or 209. The valve is of theVickers type, Model DG454-020C. The plate 139 is shifted in a planethrough the trunnions 166 of the swash plate. While the figure shows theplate as being movable vertically, actually it is disposed 90 from theposition shown in the figure to operate in a horizontal plane. A pair ofcylinders 211 and 212 are provided in the walls of the fixed casing 120.The piston 193 and the piston 213 on the plate register within therespective cylinders 211 and 212. The cylinders center the pistons andthe plate relative to the center line of the pump and the motor. Springs215 and 216 are disposed within the cylinders 211 and 212 respectivelyfor maintaining the plate in centered relation relative to the shaft121. The springs are of like characteristics but since the plate isshown as being shifted it will be noted that one spring is showncompressed. The conduit 208 is connected to the cylinder 211 while aconduit 209 is connected to the cylinder 212. The valve 205 is employedfor shifting the plate 139 from neutral position to forward or reversepositions so that the vehicle may be driven in either the forward orreverse direction.

When the operator is ready to drive the car, he first turns on theignition key and starts the engine. The forward button is then pressedif he desires the car to move forwardly, or if he desires to back upthen the reverse button is pressed. Upon pressing the forward button,the valve 205 shifts from neutral to forward position, applying fluid toone of the cylinders 211 or 212 which at idling engine speed is notsuflicient to shift the plate 139. At this time the swash plate will bein its maximum angular position due to the action of the spring 176which overcomes any vacuum from the conduit 185. When the operatordesires to drive the vehicle, the accelerator is advanced, speeding upthe engine and increasing the oil pressure in the conduit 186 which isdelivered to one or the other of the cylinders 211 or 212, to therebyshift the plate 139. It is to be understood that when the engine isstarted the shaft 121 is driven, driving the pump gears 123 and 132without building any substantial pressure within the system when theplate 139 is in neutral position. The flow of fluid will pass from theoutlet passageways 137 about the plate 139 through the recess 144 intothe intake passageways 138 of the plate 136 of the pump, thus freelycirculating the oil within the system. It will be noted that the innerwall 220 of the plate 139 is of narrower width than the width of therecesses 155, permitting the circulation of oil when the plate is inneutral position. When the plate is shifted, the free flow of oil isinterrupted and the high pressure oil is delivered to the cylinder 148of the motor 140 when at one area of the plate during the rotation ofthe motor relative thereto and delivered therefrom into the intakepassageways to the pump 119 at the opposite area of the plate 139.

From Fig. 14 it will be noted that the fluid from the pump 119 is alwaysdelivered within the central opening 141 and that the return oil passesinto the recesses 152, 153 and apertures 151 to the intakepassageway'138 of the pump. It will be noted further from Fig. 14 thatone-half of one side of the plate 139 has a face 222 which is disposedin sealed relation to the face of the plate 136. The face 222 cuts otfone of the three inlet passageways 138 at all times during the relativerotation between the pump and the plate 139 when the plate is shifted toa position for reversing the drive of the shaft 128, When in thisposition the fluid from the pump 119 to the motor is applied on theopposite side from that when the vehicle is driven in a forwarddirection, thereby applying the torque in reverse direction from theshaft 121 to shaft 128 and thereby reversing the direction of operationof the vehicle. The capacity of the pump 119 is such as to deliverfifteen cubic inches of fluid each revolution of the central gear 123relative to the pump housing 127. The motor 140 has a capacity forconsuming forty-five cubic inches of fluid during a single rotation ofthe swash plate 162 relative to the trunnion ring when the swash plateis at maximum angular position. The maximum difference in rotationbetween the shafts 121 and 128 will be the rate of consumption of oil bythe motor to that delivered by the pump plus one, which gives a maximumratio of four to one. It is understood that the ratio will vary from oneto one to four to one, depending upon the angular position of the swashplate 162. When the plate 139 is in a position to reverse the drive ofthe vehicle, the ratio between the shafts 121 and 128 will be thecapacity of consumption of the motor divided by the capacity of the pumpless one, and in this instance would be two to one. It is for thisreason that the face 222 is provided to the plate 139 so that the facewill be in a position to cut out one of the three intake passageways 138when the plate 139 is set for reversing the drive for the vehicle. Thischanges the capacity of the fluid delivered by the pump from fifteencubic inches per relative revolution to ten cubic inches per relativerevolution, thereby producing a ratio of substantially 3 /2 to 1 inreverse.

It will be noted that a passageway 223 is provided in the face 222 ofthe plate 139 for the purpose of supplying oil to the passageways 224when a suction occurs in the passageways 138 if sufficient oil is notsupplied from the cylinders 148. The oil in the slot 223 prevents airfrom being sucked into the pump and mixed with the oil, providing amixture which would be compressible. The slot is effective only duringreverse operation of the vehicle when the plate 139 is in reverseposition. Slots 225 are provided in the face 222 of the plate 139 topermit the free flow of oil from one area of the plate to the other,thereby equalizing the flow of oil in the plate before it is deliveredto the pump 119.

The tilted position of the swash plate 162 controls the amount of oilthat can be consumed by the cylinders of the motor 140. When the swashplate is in vertical or no-stroke position, then no oil can be consumedby the cylinders and a head of oil under pressure will be provided bythe pump due to the tendency of the gear 123 to drive the gears 132 andthe pump body 136. In this relationship, a direct drive will occur fromthe engine to the shafts 121 and 128.

When starting from stop position, the swash plate 162 is at its greatestangular position and the plate 139 is shifted to a position fordelivering oil to the motor cylinders in one area of the plate and fordischarging oil from the cylinders at an opposite area of the plate toreturn the fluid to the adjacent intake passageways 138 of the pump 119.This will give a four to one ratio and the greatest degree of torque atthe time of starting the forward movement of the vehicle. As the vehiclemoves forward, the gears 177 and 178 drive the shaft 179 and the pump181. The fluid pressure built up by the pump 181 in the conduit 182 willreach a desired amount and will apply a pressure to the rear side of thepiston 174, tending to move it to the forward end of the cylinder 172against a maximum pressure applied to the interior of the piston rod173. The greater area of the piston 174 will overcome the pressure onthe rod 175, thereby per- 13 mitting the piston 174 to move toward theforward end of the cylinder. This will occur when the speed of the shaft128 has increased a sufficient amount to drive the pump 181 at a higherspeed, thereby increasing the oil pressure on the rear of the piston174. The speed requirement of the shaft 128 to produce the necessary oilpres sure on the back of the piston 174 to shift the piston is dependentupon the amount of pressure which is applied to the hollow piston 173.As the torque requirement of the wheels of the vehicle increases, thepressure of oil delivered to the cylinders 148 increases, therebybuilding up pressure in the hollow piston 173, tending to move itoutwardly against the pressure on the rear of the piston 174. As thetorque requirement increases, the piston 174 will move to the rear ofthe cylinder 172, permitting the swash plate 162 to move from a verticalposition or from an angular position to a greater angular position, asthe case maybe, thereby increasing the mechanical advantage of the motor140 and its oil consumption and thereby providing a lower ratio betweenthe shafts 121 and 128. If constant speed of travel of the vehicle isdesired when the tractive load increases, it is necessary to increasethe speed of the engine. If the engine speed remains constant, thevehicle will be driven at a lower speed. However, torque will be appliedfrom the motor 141 to the shaft 128, thereby increasing the drivingtorque on the wheels while reducing the drop in speed. It is to beunderstood that the speed of the engine may be changed to maintain thespeed of the vehicle constant while the additional torque is beingapplied through the operation of the gears of the pump 119 relative tothe case, supplying oil to the cylinders of the motor 140 to operate thepistons thereon, the length of stroke of which is dependent upon abalance between the torque requirement and the driving speed of thevehicle.

It will be noted from Fig. 9 that the conduit 185 connected to thecylinder 172 on the forward side of the piston 174 is available toassist in urging the swash plate 162 to its vertical or no-strokeposition. It will be understood that if the vacuum is decreased due toinefficient engine operation, then this tendency is reduced, making iteasier to shift the swash plate from vertical or no-stroke position,thereby lowering the ratio of the drive. It will be noted that theconduit 183 has a fluid pressure operated switch 226 connected thereinwhich is connected to the control circuit in such manner as to preventthe plate 139 from being shifted to reverse position so long as the pump181 is being driven at sufficient speed to maintain a desired pressureof oil within the conduit.

Referring to the wiring diagram of Fig. 15, when the ignition switch 230is closed, the starter switch 231 may then be closed through a circuitto the starter through the contacts 23.2 and 233 of the forward relay234 and the reverse relay 235, respectively. When the forward button 236is shifted, contacts 237 are open and contacts 238 are closed. Thiscompletes a circuit to the solenoid 206 for shifting the valve 205, tothereby shift the plate 139 to a position for moving the vehicleforwardly. The closing of the contacts 238 energizes the coil 239 of therelay 234, thereby opening the contacts 232 and closing the contacts241. This provides a holding circuit across the contacts 238 which willopen upon the release of the button 236. The plate 139 may be returnedto neutral position at any time upon pressing the neutral button 242 orturning the ignition switch 231) to off position, thereby opening thecircuit to the coil 239 of the relay 234 and returning the contacts tothe position illustrated in the drawing. If the motor dies duringoperation and the ignition switch is closed, the closing of the starterswitch will not energize the starter motor so long as either of thecoils of the relays 234 or 235 is energized. This is due to the factthat the contacts 232 and 233 are in open position.

The switch 226 is normally closed but when pressure is present'in theconduit .183 these contacts open, thereby opening the ground to therelay 235 and the solenoid 207 tion. If the reverse button 243 ispressed, either whenthe system is in neutral position or when in forwardposition when the contacts 226 are closed, the contacts 244 are openedand contacts 245 are closed, thereby energizing the coil 246 of therelay 235 and also the solenoid 207 and opening a circuit to the forwardrelay 234 by opening the contacts 233 and closing contacts 247. Theenergization of the solenoid 207 shifts the spool of the valve 205 sothat the plate 139 is shifted to the reverse position pointed outhereinabove. 'When in this position, the pump gears will operate toproduce pressure which will be applied to the cylinders of the motor 140approximately 180 from the application of fluid pressure when the platewas in forward position, to thereby reverse the direction of applicationof thetorque from the shaft 121 to shaft 128, to thereby reverse thedirection of movement of the vehicle. It is to. be understood that whenreversing the vehicle the swash plate must be maintained in its maximumangular position so that a drive will occur between the fluid from thepump 119 to that of the cylinders and pistons of the motor 140. It isonly through the drive of the motor casing and the pump casing in areverse direction that a torque in the reverse direction is produced tothe vehicle wheels. The swash plate 162 is retained at its maximumposition due to the fact that the pump 181 is being driven in a reversedirection, eliminating any pressure to the cylinder 172 while a maximumpressure is being applied to the hollow interior of the piston rod 173to urge the piston rod to the right, assisted by the spring 176. It isto be understood, therefore, that the reversal can occur only when adrive exists between the pump 119 and the motor 140. Thus, it willbe'seen that by driving the shaft 121 in the same direction as whendriving the vehicle forwardly, the change in the flow of fluid from thepump 119 to the motor when the plate 139 is shifted to reverse positionproduces the opposite rotation of the shaft 128. This occurs because theplate 139 has been shifted to have the pressure applied to the pistonsof the motor at a point from the point where the pressure was deliveredwhen driving the vehicle forwardly. When the oil is delivered to thepistons in this manner, the reverse rotation of the swash plate 162occurs, which thereby reverses the rotation of the motor casing.Sufiicient mechanical advantage or f'orce'is provided to reverse thedirection of rotation of the pump casing to which the shaft 128 isdirectly connected, to thereby produce the reverse rotation of the shaft128 and the movement of the vehicle in a reverse direction.

It will be understood that the specific capacities of the I pump 119 andmotor 140 were herein referred to merely by way of example and are in noway limiting, as the rate of delivery of either the pump or motor or'both may be changed to meet the requirement of a specific installation,that of a vehicle or of an industrial application.

What is claimed is:

1. In a variable ratio hydraulic transmission of the characterdescribed, a drive shaft, a driven shaft disposed in aligned relation tosaid drive shaft, a fixed capacity pump having an inlet and an outletand comprising first and second relatively rotatable elements one beingsecured to said drive shaft the other secured to said driven shaft, avariable capacity fluid motor having first and second relatively movableelements disposed about said drive shaft and driven by the fluidpressure developed by 15 shaft, said fluid motor being responsive to thepressure of the fluid at the outlet of said pump.

2. In a transmission, a drive shaft, a driven shaft disposed in alignedrelation to said drive shaft, a fixed capacity pump having an inlet andan outlet and comprising first and second relatively rotatable elementsone being secured to said drive shaft the other secured to said drivenshaft, a variable capacity fluid motor having first and secondrelatively movable elements disposed about said drive shaft and drivenby the fluid pressure developed by said pump, means interconnecting thedriven means of said fluid motor to said driven shaft for driving theshaft in the same direction as'said shaft is driven by the pump, meansfor reversing the flow of fluid from the pump to said motor when saidfluid motor is set for full capacity to thereby reverse the rotation ofsaid motor and the movable element of the pump which is secured to saiddriven shaft to thereby reverse the rotation of said driven shaft, saidfluid motor being responsive to the pressure of the fluid at the outletof said pump.

3. In a transmission, a drive shaft, a driven shaft disposed in alignedrelation to said drive shaft, a fixed capacity pump having an inlet andan outlet and comprising first and second relatively rotatable elements,one being secured to said drive shaft, the other secured to said drivenshaft, a variable capacity fluid motor having first and secondrelatively movable elements disposed about said drive shaft and drivenby the fluid pressure developed by said pump, means interconnecting thedriven means of said fluid motor to said driven shaft for driving theshaft in the same direction as said shaft is driven by the pump, meansfor reversing the flow of fluid from the pump to said motor when saidfluid motor is set for full capacity to thereby reverse the rotation ofsaid motor and the movable element of the pump which is secured to saiddriven shaft to thereby reverse the rotation of said driven shaft, saidfluid motor being responsive to the pressure of the fluid at the outletof said pump, spring means for assisting said fluid pressure developedby said pump to change said motor capacity, an engine arranged fordriving said drive shaft, and vacuum means for said engine opposing saidspring pressure for varying the capacity of the motor in accordance withthe load on said engine.

4. In a variable ratio hydraulic transmission of the characterdescribed, a drive shaft, a driven shaft disposed in alignment relationto said drive shaft, a fixed capacity pump having an inlet and an outletand comprising first and second relatively rotatable elements, one beingsecured to said drive shaft and the other secured to said driven shaft,a variable capacity fluid motor having first and second relativelymovable elements disposed about said drive shaft and driven by the fluidpressure developed by said pump, means for varying the capacity of saidmotor to change the speed of said'driven shaft relative to said driveshaft while varying the torque capacity thereof, a shiftable valve platehaving spaced passageways therethrough for the passage of fluiddelivered by said pump, said plate being disposed between said pump andmotor and which in neutral position directs the passage of fluid fromthe high to the low side of said pump, means for shifting said plate toforward drive position to adjust the motorfor driving directly throughsaid shafts and for indirectly driving said shafts when the pumpsupplies fluid to said motor by the relative rotation of portionsthereof to change the relative. speed of the shafts, in. one sense andthe torque output thereof in the oppositesense, means for varying thecapacity of said motor in response to the delivered pump pressure, andmeans for varying the capacity of the motor in the opposite sense inresponse to the speed of rotation of said motor.

5. In a variable ratio hydraulic transmission of the 16 characterdescribed, a drive shaft, a driven shaft disposed in alignment relationto said drive shaft, a fixed capacity pump having an inlet and an outletand comprising first and second relatively rotatable elements, one beingsecured to said drive shaft and the other secured to said driven shaft,a variable capacity fluid motor having first and second relativelymovable elements disposed about said drive shaft and driven by the fluidpressure developed by said pump, means for varying the capacity of saidmotor to change the speed of said driven shaft relative to said driveshaft while varying the torque capacity thereof, a slidable valve platehaving spaced passageways therethrough for the passage of fluiddelivered by said pump, said plate being disposed between said pump andmotor and which in neutral position directs the passage of fluid fromthe high to the low side of said pump, means for shifting said plate toforward drive position to adjust the motor for driving directly throughsaid shafts and for indirectly driving said shafts when the pumpsupplies fluid to said motor by the relative rotation of portionsthereof to change the relative speed of the shafts in one sense and thetorque output thereof in the opposite sense, means for Y varying thecapacity of said motor in response to the delivered pump pressure, meansfor varying the capacity of the motor in the opposite sense in responseto the speed of rotation of said motor, and a spring for assisting thepump pressure to change the capacity of said motor.

6. In a variable ratio hydraulic transmission of the characterdescribed, a drive shaft, a driven shaft disposed in alignment relationto said drive shaft, a fixed capacity pump having an inlet and an outletand comprising first and second relatively rotatable elements, one beingsecured to said drive shaft and the other secured to said driven shaft,a variable capacity fluid motor having first and second relativelymovable elements disposed about said drive shaft and driven by the fluidpressure developed by said pump, means for varying the capacity of saidmotor to change the speed of said driven shaft relative to said driveshaft while varying the torque capacity thereof, a slidable valve platehaving spaced passageways therethrough for the passage of fluiddelivered by said pump, said plate being disposed between said pump andmotor which in neutral position directs the passage of fluid from thehigh to the low side of said pump, means for shifting said plate toforward drive position to adjust the motor for driving directly throughsaid shafts and for indirectly driving said shafts when the pumpsupplies fluid to said motor by the relative rotation of portionsthereof to change the relative speed of the References Cited in the fileof this patent UNITED STATES PATENTS 1,840,864 Rayburn et al. Jan. 12,1932 1,840,869 Rayburn Ian. 12, 1932 1,840,876 Rayburn Jan. 12, 19322,114,076 6612 Apr. 12, 1938 2,190,122 Mohler Feb. 13, 1940 2,389,186Dodge Nov. 20, 1945 2,547,578 Holmes Apr. 3, 1951 2,629,332 Tripp Feb.24, 1953 2,706,384 Schott Apr. 19, 1955

